Choke plug for air brakes



Dec. 31, 1935.

CHOKE PLUG FOR AIR BRAKES Filed Nbv. 26, 1954 ISmJentor JZQ/wi/a 6L. SqFl o/z attorneys L. SAFFORD 2,025,905

Patented Dec. 31, 1935 U [TED STATES CHOKE PLUG FOR AIR BRAKES Lewis A. Safiord, Watertown, N. Y., assignor to The New York Air Brake Company, a corporation of New Jersey Application November 26, 1934, Serial No. 754,924

3 Claims.

This invention relates to fluid pressure brakes, and provides a so-called choke plug or flow restricting orifice element having improved means for preventing clogging of the restricting orifice.

In the air brake art, it is common practice to make use of choke plugs to control the rate of flow for various purposes. Precise control of the rate of flow is frequently essential to the satisfactory operation of the brakes. Improper functioning or failure to function is likely to occasion serious accidents and consequently an exceptionally high standard is imposed on the periormance of these choke plugs.

In the patent to Work, No. 1,919,408, issued July 25, 1933, there is disclosed a choke plug protected on the approach side by means forming a very narrow annular passage, the width of such annular passage being less than the diameter of the circular choke port. Protection of this type is effective, except against thin particles of scale which can pass through the annular passage. While they cannot enter the choke port, they can blind the choke port.

The object of the present invention is to eliminate even this possibility. The result is accomplished by so forming the narrow annular passage as to provide a sharp angle turn in the path of flow, conveniently a right angle turn. In this way, the entrance of thin fiat scales is precluded.

Another feature of the invention is the construction of the device in such a way that it is susceptible ,of being produced by simple and inexpensive manufacturing operations, and may be dismounted for cleaning.

A preferred embodiment of the invention will now be described with reference to the accompanying drawing, in which:--

Fig. l is a longitudinal axial section of the choke plug on a greatly enlarged scale; and

Fig. 2 is a section on the line 22 of Fig. l.

The choke plug is made up of two components, a body and a guard, which, when assembled, are retained frictionally in assembled relation. The body 6 is shown as a cylindrical plug which may be pressed into a drilled port, according to current practice, but, so far as the invention is concerned, it is immaterial how it is mounted in place provided leakage around the body is precluded.

The flow restricting port is shown as a simple drilled port 1, but might take any special form known in the choke port art, various forms having been designed with the idea of precluding the accumulation of obstructions in the port.

The body 6 is counterbored from the end reas about one-third the total depth or the counterbore 8, but this dimensional relation is not important.

The guard member comprises a head I l and a sleeve l2, sleeve I2 being of such diameter as to make a frictional fit in the counterbore 8, and of such length that the head I l is spaced from the end of body 6 to form a narrow annular port [3 whose width approximates, but does not necessarily equal, the width of the annular port I4 formed by the interval between the outer wall of sleeve l2 and the counterbore 9.

The sleeve I2 is hollow or counterbored, as shown, and is provided with a transverse slot [5 which is long enough to overlapthe passage I l and provide free flow to the choke port I. It will be understood that air approaching the choke port 1 enters through the annular passage l3, passes at right angles from the port I3 into the narrow annular port l4, and finally reaches that portion of the slot l5 which overlaps the passage l4. Thence, it flows through the choke port I to the point of use.

No particle large enough to clog the port I can pass through the passages l3 and l4,'and even a thin flat plate-like scale which might be large enough to blank the port l would be arrested because of its inability to turn the angle between the planeannular passage I 3 and the cylindrical annular passage l4. Consequently,- the port 1 is protected against all types of obstructing bodies.

A decided advantage of the construction shown is that the guard member may be withdrawn from the body 6 for cleaning. The particular plug chosen for illustration is for that type of choke port in which the flow is uni-directional and the guard is placed on the approach side. Where the choke controls a reversible flow, the guard structure illustrated can be duplicated without the exercise of invention, and accordingly, it is deemed unnecessary to illustrate such duplicate construction.

What is claimed is:.

1. The combination of means forming a choke port, and means forming an approach passage leading thereto, said passage including two-communicating portions arranged serially to produce an abrupt change of direction, both portions being narrower than the diameter of said port and of sufiicient length to afford flow capacity in excess of that of'the port.

2. A flow controlling choke device comprising a member having a choke port and a guard member frictionally assembled in telescoping relation therewith, said members defining between them an approach passage leading to said port and comprising two annular portions communicating at an abrupt angle with one another, both portions being narrower than the diameter of said port and of sufficient circumference to afford flow capacity in excess of that of the port.

3. A flow controling choke device comprising two members assembled in telescopic relation with each other, one of said members having a choke port and the two members when assembled defining an approach passage leading to said port, said passage being made up of two parts, a plane annular slot narrower than the diameter of said choke port, and an approximately cylindrical annular passage also narrower than the diameter of said choke port and intersecting said plane annular passage, the circumferences of said annular passages being such that the flow capacity of the annular passage aiforded thereby exceeds the flow capacity of the choke port.

LEWIS A. SAFFORD. 

